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The Himalayas are experiencing considerable warming due to global climate change, significantly affecting precipitation patterns. Our analysis of precipitation and temperature trends over the last four decades (1981–2023) and the estimation of climatic extreme indices (Z-statistics of trend analysis derived from Mann–Kendall’s S-statistics and cross verified by Sen’s slope analysis) in the Indus–Ganges–Brahmaputra (IGB) watersheds reveals important findings. Precipitation is increasing in the Indus basin, with both pre-monsoon and monsoon strengthening while decreasing in the Ganges and Brahmaputra basins. The entire Himalayan belt shows a remarkable positive increment in the daily maximum temperature; however, the western Himalayas show a more prominent temperature rise during the pre-monsoon period, whereas the middle and the eastern Himalayas experience temperature rise during the post-monsoon period. These changes are likely linked to various interconnected climatic and atmospheric factors, such as orographic effects, shifting temperature gradients due to climate change, strengthening Western Disturbances, interactions between the monsoon and mid-latitude circulation, and rising cyclonic activity in the Arabian Sea. The decrease in precipitation in the Ganges and Brahmaputra regions could be attributed to atmospheric circulation changes, including the Quasi-Biennial Oscillation (QBO) and the El Niño Southern Oscillation (ENSO), the uplift of the Shillong Plateau causing a rain shadow effect, and reduced land–ocean temperature gradients. Warming is particularly pronounced in the Eastern Himalayas compared to the central and western regions, as evidenced by an increased maximum of daily maximum temperature (TXx), a minimum of daily maximum temperature (TXn), and a maximum of daily minimum temperature extremes (TNx), alongside a decrease in the Ice Days (ID). These trends may indicate a higher risk of Glacial Lake Outburst Floods (GLOFs) in the future. Compared to the Hindu Kush, Western, and Central Himalayas, the Eastern Himalayas face a greater frequency and intensity of GLOFs. The significant regional warming accelerates glacier melting, contributing to the formation and expansion of glacial lakes. Ongoing monitoring and effective risk management strategies are crucial to mitigating the impacts of these natural hazards.

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Regional Warming and Its Impact on Precipitation Patterns in the Indus–Ganges–Brahmaputra Watersheds: Implications for Glacial Lake Outburst Floods

  • 章节

  • 发表日期：

    2025年

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  • Monisha Chetia,
  • Siddhartha Kumar Lahiri

摘要

The Himalayas are experiencing considerable warming due to global climate change, significantly affecting precipitation patterns. Our analysis of precipitation and temperature trends over the last four decades (1981–2023) and the estimation of climatic extreme indices (Z-statistics of trend analysis derived from Mann–Kendall’s S-statistics and cross verified by Sen’s slope analysis) in the Indus–Ganges–Brahmaputra (IGB) watersheds reveals important findings. Precipitation is increasing in the Indus basin, with both pre-monsoon and monsoon strengthening while decreasing in the Ganges and Brahmaputra basins. The entire Himalayan belt shows a remarkable positive increment in the daily maximum temperature; however, the western Himalayas show a more prominent temperature rise during the pre-monsoon period, whereas the middle and the eastern Himalayas experience temperature rise during the post-monsoon period. These changes are likely linked to various interconnected climatic and atmospheric factors, such as orographic effects, shifting temperature gradients due to climate change, strengthening Western Disturbances, interactions between the monsoon and mid-latitude circulation, and rising cyclonic activity in the Arabian Sea. The decrease in precipitation in the Ganges and Brahmaputra regions could be attributed to atmospheric circulation changes, including the Quasi-Biennial Oscillation (QBO) and the El Niño Southern Oscillation (ENSO), the uplift of the Shillong Plateau causing a rain shadow effect, and reduced land–ocean temperature gradients. Warming is particularly pronounced in the Eastern Himalayas compared to the central and western regions, as evidenced by an increased maximum of daily maximum temperature (TXx), a minimum of daily maximum temperature (TXn), and a maximum of daily minimum temperature extremes (TNx), alongside a decrease in the Ice Days (ID). These trends may indicate a higher risk of Glacial Lake Outburst Floods (GLOFs) in the future. Compared to the Hindu Kush, Western, and Central Himalayas, the Eastern Himalayas face a greater frequency and intensity of GLOFs. The significant regional warming accelerates glacier melting, contributing to the formation and expansion of glacial lakes. Ongoing monitoring and effective risk management strategies are crucial to mitigating the impacts of these natural hazards.